Real-time Earth and Moon phase

Tuesday, June 28, 2011

After scouting the treacherous seas off Port MacDonnell for nearly four hours a feeble hand waved from the water showing signs of life from two courageous survivors. In pitch-black freezing water two men suffering from hypothermia clung to an esky for dear life. Two other men threw them a life-ring as relief washed over their faces.

That was happened in South Australia,as reported in the abc.net by Tash Impey. Here's the report:

Had it not been for the heroic deeds of local fishermen Gary Causon and Mark Moody these two Geelong men may not have seen another sunrise.

When two freak waves hit and subsequently capsized the vessel of Mike Fisher and Brad Neicho 15 kilometres off the coast of Port MacDonnell on Saturday a massive search and rescue operation was undertaken to bring these men back alive.

Skipper Moody and fellow fisherman Causon pulled them to safety onto the aptly named boat Remarkable.

"It was very remarkable named after my boat. It was very cold and I don't know how they lasted that long," said Mr Moody of the lucky men.

After a helicopter circled the area three times and failed to pick up the men bobbing in swells three and half-metres high, it was not until hours later that the infrared light from a Tasmanian search and rescue aircraft finally located the men.

Upon spotting the men through the aircraft's light, Causon said he was amazed to see a response from the water.

"They weren't real good I thought they were already gone until he actually waved.

"I think if it had of been another fifteen minutes or so they said they would have had to let go because they couldn't hold on anymore," he said.

Hauling the freezing six foot tall men onto the boat required enormous effort, said Causon.

"It wasn't easy to do they were big men. It took us all of our strength to lift them into the back of the boat".

Sunday, June 26, 2011

When I first saw the title "Freak wave in the high seas" of this article of Discovery News published a couple of days ago, I thought it's another science writer's rehash kind. I was wrong! Unbeknown to me at the time that the author of the article, Kiern Mulvaney, is actually a real sea going writer who was the author of the book "Whaling Season" and "At the end of the earth" among many others. He really knows what he was talking about in this article:

It was February 1993, and we were nearing the end of a Southern Ocean voyage that could charitably be described as vexing. A Force 11 pounded us, wave after wave coating the decks with bitterly cold water that rapidly froze into layer upon layer of ice. Our captain turned us into the storm, the wind so strong that even with the engines on full ahead the ship was making but a few knots. Overnight, as we struggled to sleep, the ship suffered a powerful blow, as I described several years later:

Nobody saw exactly what happened, but as best as anyone could figure out, the ship was hit broadside by an enormous freak wave. the wave was so powerful that it lifted the two-and-a-half ton Hurricane [a rigid-hulled inflatable boat] up in its cradle, snapping the straps that secured it in place. Only the stanchion next to the boat cradle prevented the boat from flying across the deck, although the pole itself buckled with the strain. Thwarted in its efforts to rip the Hurricane free of its shackles, the wave threw itself across the deck and slammed into the helicopter

The jolt from the wave shook the ship and its occupants; a few poked cautious heads out on to deck to survey the damage, and in the dusk saw the helicopter splayed sadly to one side, its leg struts snapped in half by the onrushing wave.

Some months later, safely back on dry land, I sat dockside and described the incident to a couple of friends who had not been on board. One, not accustomed to long spells on the open ocean, seemed disbelieving; if we had been steering into the waves, how could one have hit us directly from starboard? The other, a captain with whom I would later return to the Antarctic, stared ahead quietly.

"The sea," he said with the air of a man who is all too uncomfortably familiar with his subject, "does strange things."

That's a fabulous first hand experience of an encounter with real life freaque wave in 1993! I am wondering if their encounter with a freaque wave ever made it into the statistics counter. Most likely not. But that was clearly a freaque wave they had encountered, eventhough "Nobody saw exactly what happened" that is probably should be another characterization for freaque waves!

All of these articles are in essence reporting the new speculations from a new paper just published in the Proceedings of the Royal society A with a paper title: "Did the Draupner wave occurs in a crossing sea?" According to the abstract of the paper:

This paper investigates the directionality of the Draupner wave and concludes it might have resulted from two wave-groups crossing, whose mean wave directions were separated by about 90° or more. This result has been deduced from a set-up of the low-frequency second-order difference waves under the giant wave, which can be explained only if two wave systems are propagating at such an angle.

I guess one special feature of this new work, unlike the previous theoretical works, is that they employed ECMWF's modeling corroboration -- what they called "backed up by a hindcast". May be that's what persuaded the media writers to come up with the optimistic headlines like "discovered" and "may be solved" to characterize the new speculation. It is just another speculation. We have no way of knowing of how do "two wave-groups crossing, whose mean wave directions were separated by about 90° or more" to come about in real oceans to produce the freaque waves.

I just wish to add that Jennifer Welsh's article included a video clip of real life freaque wave encounter from the Discovery Channel TV show "The Deadliest Catch" that's well worth watching! And I find myself being intrigued by the title "On the crest of a freak wave" so much so that I choose to use it for the title of this posting today. Really, how do you feel or what do you see if you can somehow manifest yourself onto the crest of a wave in the ocean? To me, I think, an immediate reaction would be to look for where is the trough. Now the trough is certainly there somewhere nearby, but most definitely it will not be directly underneath the crest as the modern conventional single point wave measurements would imply! This new paper stems from thinking about the directional spreading -- an antiquated conceptualization of the late 1950's. In the 2nd decade of the 21st century, isn't it timely for us to think about spatial wave measurement now?

Tuesday, June 14, 2011

Wow! NASA has discovered that there's surf wave in the Sun! Here's the news report in the World Bulletin:

"The waves we''re seeing in these images are so small," said Thompson. "But they''re only the size of the United States," she said.

Kelvin-Helmholtz instabilities usually occur when two fluids of different densities or different speeds flow by each other. In the case of the solar atmosphere, which is made of a very hot and electrically charged gas called plasma, the two flows come from an expanse of plasma erupting off the sun''s surface as it passes by plasma that is not erupting.

On May 15, Russell Hayley, his 16 year-old-son Brodie and his mate Geoff, all from Albury, went fishing off Hoyers Reef about half a nautical mile offshore, near the entrance to Wallaga Lake.

The sky was blue, the swell was small and Russell was sitting back having a cup of coffee. He looked around and saw a large wave swelling of the reef.

He got to the ignition and turned it on but did not have time to put the boat into gear.

The boat rode out the first wave but unfortunately there was a second bigger breaking wave immediately behind.

The second wave rolled the boat. Russell and his son were tipped out but unfortunately Geoff was trapped under water.

He managed to get out about 15 seconds later.

They retrieved lifejackets from the boat. Brodie, a strong swimmer, swam for shore to raise the alarm while Russel stayed to assist his mate who had a severe gash and a broken leg. Russell then towed Geoff to shore.

Geoff was airlifted away at about 2.30pm. Marine Rescue, the surf patrol, the police and ambulance and rescue helicopter attended the incident.

This report has provided more details on what had happened than one could expect and the unexpectedness of the incident was described quite vividly and with a little poetic flavor. It was two waves in this case that caused the damage.

But again it's good that all are safely rescued and a happy ending by any means. Of particular interest to me is this comment by the commander of the Marine Rescue unit:

“With a bommie or shallow reef like Hoyer’s Reef, the waves can stand up very quickly out of nowhere so always be aware of where these are and stay well away.”

Now as I alluded to yesterday, this should be theoretically feasible to manifest -- may not be the out of nowhere part. So here is interestingly another new (?) implication on freaque waves occurrences that has not been examined by the freaque waves community -- it can happen over an underwater mount. Indeed, beware the bombora!

Monday, June 06, 2011

Two commercial fishermen have been rescued after big seas damaged their boat south of Narooma, on the New South Wales far south coast.

The men were fishing near a bombora about 2km off Wallaga Lake yesterday.

They were treated by ambulance officers after being towed back to shore by Bermagui Marine Rescue.

As usual, not much information about the waves that caused the damage. But anything that can have the word "lucky" attach to it should always be good news. For me two things are educational here. First, for us outsiders a little geography lesson, Wallaga Lake is "296 km southwest of Sydney, Australia" according to Wikipedia. And secondly the word "bombora" is a strange new word for me. Again Wikipedia has these to say:

Bombora is an indigenous Australian term for an area of large sea waves breaking over a shallow area such as a submerged rock shelf, reef, or sand bank that is located some distance from the shoreline and beach surf break. As the wave passes over the shallow area its shape is raised and steepened, creating a localised wave formation. The size and shape of bombora waves makes them attractive to surfers willing to take the risk of riding what is generally considered a hazardous pursuit. These formations can pose a significant danger even in good weather as a bombora may not be identifiable because it may not always have breaking waves.

I am wondering if my Australian friends know about all of these! Now the description "As the wave passes over the shallow area its shape is raised and steepened, creating a localised wave formation . . ." seems to have a very distinctive theoretical flavor. May be all wave books should have a chapter on bombora waves! So here we are, bombora waves, anyone?

Sunday, June 05, 2011

On a hot summer day in the northern hemisphere, it's natural to find an article about Antarctica adventure interesting. I am talking about the article in Sydney Morning Herald entitled "In memory of Mawson" a couple of days ago. The memory is about Sir Douglas Mawson's historic 1911-14 expedition, according to the article "it's timely to remember one of the great Antarctic heroes of the 20th century. An Australian geologist from Adelaide, Mawson was on Shackleton's 1908-09 Nimrod expedition." I guess for those of us who might not have heard of Sir Mawson, we have at least heard of Sir Ernest Henry Shackleton -- that's how I got interested in reading the article in the first place. It's a rather long article, I am not very certain if this is a travelogue about his adventure on the Antarctic cruise or advertise it as travel report. Nevertheless it's a good article to read. I am especially intrigued by this paragraph:

The swell builds all day until, that night, it peaks at 10 metres. At dinner, we hold on to our plates and watch the windows of the dining room submerge, like the doors of front-loading washing machines on the rinse cycle. After dessert, a few of us put on wet-weather jackets and stand at the stern railing watching a procession of monster waves chasing us, the 90km/h winds blowing rain squalls and salt spray in our faces, until a couple of rogue waves catch up to the ship and splash over the aft deck, forcing us inside. It's a rolling night; the sea breathes deeply under us.

Somehow the writer alluded to freaque waves very casually as "a couple of rogue waves catch up to the ship and splash over the aft deck, forcing us inside" but no panic, no damage, no big deal as one might imagine when a cruise ship encounters the freaque waves. The academic freaque waves community still has yet to come up a viable definition, the cruise shipping folks seems to have already taken it for granted -- no big deal!

Anyway I find the article is educational for me to learn some more about historical Antarctica expeditions. I don't think I might be interested in participating in one of those cruises, but it is always of interest to read someone else' adventures. Oh, yes, at the end of the article there is this note: "Louise Southerden travelled courtesy of Orion Expedition Cruises." So the author is indeed obligated to advertise his cruise adventure. Is that the reason why he talked about the freaque wave encounters so unexcitingly?